// Copyright (c) 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef NET_QUIC_CRYPTO_AEAD_BASE_ENCRYPTER_H_
#define NET_QUIC_CRYPTO_AEAD_BASE_ENCRYPTER_H_

#include <stddef.h>

#include "base/compiler_specific.h"
#include "base/macros.h"
#include "net/quic/crypto/quic_encrypter.h"
#include "net/quic/crypto/scoped_evp_aead_ctx.h"

namespace net {

// AeadBaseEncrypter is the base class of AEAD QuicEncrypter subclasses.
class NET_EXPORT_PRIVATE AeadBaseEncrypter : public QuicEncrypter {
public:
    AeadBaseEncrypter(const EVP_AEAD* aead_alg,
        size_t key_size,
        size_t auth_tag_size,
        size_t nonce_prefix_size);
    ~AeadBaseEncrypter() override;

    // QuicEncrypter implementation
    bool SetKey(base::StringPiece key) override;
    bool SetNoncePrefix(base::StringPiece nonce_prefix) override;
    bool EncryptPacket(QuicPathId path_id,
        QuicPacketNumber packet_number,
        base::StringPiece associated_data,
        base::StringPiece plaintext,
        char* output,
        size_t* output_length,
        size_t max_output_length) override;
    size_t GetKeySize() const override;
    size_t GetNoncePrefixSize() const override;
    size_t GetMaxPlaintextSize(size_t ciphertext_size) const override;
    size_t GetCiphertextSize(size_t plaintext_size) const override;
    base::StringPiece GetKey() const override;
    base::StringPiece GetNoncePrefix() const override;

    // Necessary so unit tests can explicitly specify a nonce, instead of a
    // nonce prefix and packet number.
    bool Encrypt(base::StringPiece nonce,
        base::StringPiece associated_data,
        base::StringPiece plaintext,
        unsigned char* output);

protected:
    // Make these constants available to the subclasses so that the subclasses
    // can assert at compile time their key_size_ and nonce_prefix_size_ do not
    // exceed the maximum.
    static const size_t kMaxKeySize = 32;
    static const size_t kMaxNoncePrefixSize = 4;

private:
    const EVP_AEAD* const aead_alg_;
    const size_t key_size_;
    const size_t auth_tag_size_;
    const size_t nonce_prefix_size_;

    // The key.
    unsigned char key_[kMaxKeySize];
    // The nonce prefix.
    unsigned char nonce_prefix_[kMaxNoncePrefixSize];

    ScopedEVPAEADCtx ctx_;

    DISALLOW_COPY_AND_ASSIGN(AeadBaseEncrypter);
};

} // namespace net

#endif // NET_QUIC_CRYPTO_AEAD_BASE_ENCRYPTER_H_
